It is controversial whether metabolic disorders of human obesity include protein metabolism. Even less information is available concerning the effect of fat distribution on protein metabolism. Therefore, a comprehensive evaluation of glucose, lipid, and protein metabolism was performed in 11 obese nondiabetic and 9 normal women whose body composition and regional fat distribution were determined. [1-14C]Leucine and [3-3H]glucose were infused in the postabsorptive state and during an euglycemic hyperinsulinemic (35-40 μU/mL) clamp combined with indirect calorimetry for assessment of leucine flux, oxidation, and nonoxidative disposal, glucose turnover and oxidation, and lipid oxidation. Fat-free mass (FFM) was estimated by a bolus of 3H2O. Subcutaneous abdominal and visceral adipose tissues were determined by nuclear magnetic resonance imaging. During the clamp, obese women had lower glucose turnover (4.51 ± 0.41 vs. 6.63 ± 0.40 mg/min · kg FFM; P < 0.05), with a defect in both oxidation (3.27 ± 0.22 vs. 3.89 ± 0.21) and nonoxidative disposal (1.24 ± 0.27 vs. 2.74 ± 0.41; P < 0.005), whereas lipid oxidation was higher during the clamp (0.49 ± 0.15 vs. 0.17 ± 0.09 mg/min · kg FFM). There was no difference in leucine flux (basal, 2.23 ± 0.17 vs. 2.30 ± 0.29; clamp, 2.06 ± 0.19 vs. 2.10 ± 0.24 μmol/min · kg FFM), oxidation (basal, 0.37 ± 0.04 vs. 0.36 ± 0.05; clamp, 0.34 ± 0.04 vs. 0.39 ± 0.06) and nonoxidative leucine disposal (basal, 1.86 ± 0.17 vs. 1.94 ± 0.26; clamp, 1.72 ± 0.20 vs. 1.71 ± 0.19) in the two groups. In obese women, basal leucine oxidation was directly related with glucose oxidation and inversely to lipid oxidation (both P < 0.05), whereas visceral adipose tissue was inversely related to leucine flux both in the basal state and during the clamp (P < 0.05). In conclusion, in human obesity, 1) rates of protein metabolism in the basal state and in the range of insulin concentrations encountered after a meal are normal; 2) protein oxidation is positively related to glucose oxidation and negatively related to lipid oxidation; and 3) visceral adipose tissue is inversely related to all parameters of protein metabolism.
|Titolo:||Protein metabolism in human obesity: relationship with glucose and lipid metabolism and with visceral adipose tissue|
|Data di pubblicazione:||1997|
|Appare nelle tipologie:||1.1 Articolo in rivista|